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Abstract

In the crystal structure of the title compound, [Mn(NCSe)2(C4H4N2)2(H2O)2], the manganese(II) cation is coordinated by two N-bonded pyrimidine ligands, two N-bonded seleno­cyanate anions and two O-bonded water mol­ecules in a distorted octa­hedral coordination mode. The asymmetric unit consists of one manganese(II) cation, located on a centre of inversion, as well as one seleno­cyanate anion, one water mol­ecule and one pyrimidine ligand in general positions. The crystal structure consists of discrete building blocks of composition [Mn(NCSe)2(pyrimidine)2(H2O)2], which are connected into layers parallel to (101) by strong water–pyrimidine O—HN hydrogen bonds.

Related literature

For a related pyrimidine structure, see: Lipkowski & Soldatov (1993). For general background to the use of thermal decomposition reactions for the discovery and preparation of new ligand-deficient coordination polymers with defined magnetic properties, see: Wriedt & Näther (2009a,b); Wriedt et al. (2009a,b).

Acknowledgments

MW thanks the Stiftung Stipendien-Fonds des Verbandes der Chemischen Industrie and the Studienstiftung des deutschen Volkes for a PhD scholarship. Moreover, we gratefully acknowledge financial support by the State of Schleswig-Holstein and the Deutsche Forschungsgemeinschaft (Project 720/3–1) and thank Professor Dr Wolfgang Bensch for the opportunity to use of his experimental facility.

supplementary crystallographic
information

Comment

Recently, we have shown that thermal decomposition reactions are an elegante
route for the discovering and preparation of new ligand-deficient coordination
polymers with defined magnetic properties (Wriedt & Näther,
2009a,
2009b; Wriedt, Sellmer & Näther, 2009a,
2009b). In our
ongoing investigation on the synthesis, structures and properties of such
compounds based on paramagnetic transition metal pseudo-halides and N-donor
ligands, we have reacted manganese(II) dichloride, potassium selenocyanate and
pyrimidine in water. In this reaction single crystals were obtained, which
were identified as the title compound by single-crystal X-ray diffraction.

The title compound of composition [Mn(NCSe)2(H2O)2(pyrimidine)2] (Fig.
1) represents a discrete coordination complex, in which the manganese(II)
cation is coordinated by two selenocyanato anions, two water molecules and two
pyrimidine ligands in an octahedral coordination mode. The MnN4O2
octahedron is slightly distorted with two long Mn–Npyrimidine distances of
2.3328 (18) Å, two short Mn–NCSe distances of 2.1840 (9) Å and two
short
Mn—OH2 distances of 2.1582 (14) Å, while the angles around the metal
center range between 86.77 (7)–93.23 (7) and 180° (Tab. 1). The coordination
of the metal center is similar to that in a related structure (Lipkowski &
Soldatov, 1993). In the crystal structure the single complexes are
connected
via strong Npyrimidine···Hwater hydrogen bonds into layers (see
Tab. 2), which are located in the crystallographic
a/c-plane (Fig. 2 and 3). The shortest intra- and interlayer
Mn···Mn distances amount to 7.2911 (5) and 9.3672 (5) Å, respectively.

Experimental

MnCl2, KNCSe and pyrimidine were obtained from Alfa Aesar. 1 mmol (126 mg)
MnCl2, 2 mmol (288 mg) KNCSe, 0.25 mmol (20 mg) pyrimidine and 3 ml water
were reacted in a closed snap-vail without stirring. After the mixture was
standing for several days at room temperature colorless block shaped single
crystals of the title compound were obtained in a mixture with unknown phases.

Refinement

All non-hydrogen atoms were refined anisotropic. The
O—H-hydrogen atoms were located in difference map, where the
bond lengths set to ideal values and were refined using a riding model. All
other H atoms were located in difference map but were positioned with
idealized geometry and were refined isotropic with Ueq(H) = 1.2
Ueq(C) of the parent atom using a riding model with C—H = 0.95 Å.

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell e.s.d.'s are taken
into account individually in the estimation of e.s.d.'s in distances, angles
and torsion angles; correlations between e.s.d.'s in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s.
planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor
wR and goodness of fit S are based on F2, conventional
R-factors R are based on F, with F set to zero for
negative F2. The threshold expression of F2 >
σ(F2) is used only for calculating R-factors(gt) etc.
and is not relevant to the choice of reflections for refinement.
R-factors based on F2 are statistically about twice as large
as those based on F, and R- factors based on ALL data will be
even larger.